1. Field of the Invention
The present invention relates to laser-assisted fabrication of optoelectronic and photonic components using deposition of optical materials on various crystalline or amorphous solid-state substrates, and, in particular, to a new method of fabrication of self-assembling microstructures, integrated optical structures, and micro-lenses on these substrates. The deposition of target material takes place as a result of interaction of the laser beam with the substrate surface being in direct contact with a liquid containing a precursor of appropriate target material.
In one preferred embodiment, the micro-lens is fabricated directly on optical fibers or light emitting devices providing improved light collimation as required for efficient laser-to-fiber pig tailing. In another preferred embodiment, the micro-lenses are fabricated on each active element of a laser diode array.
The method can be used in all applications where controllable deposition of inorganic or organic materials on a solid state substrate is required, including chemical vapor deposition (CVD) of thin films, fabrication of self-assembling microstructures and integrated optical, fiber-optical, and micro-optical components for optoelectronic and photonic devices.
2. Information Disclosure Statement
Controllable deposition of various materials and thin films on solid-state substrates offers the most efficient and flexible means for fabrication of different optoelectronic and photonic devices. Currently the well-developed technologies of chemical vapor deposition (CVD) or metal-organic chemical vapor deposition (MOCVD) are used for fabrication of thin films of various optical materials, while chemical etching is usually employed for manufacturing of various integrated-optical and shaped micro-optical structures on appropriate solid-state substrates. The mature CVD and MOCVD technologies, however, are rather expensive; they require special clean room facilities and complicated equipment. A flexible method for room temperature deposition of various inorganic or organic target materials onto different solid-state substrates could have dramatic impact on development of the entire optoelectronic and photonic industry.
The proposed invention suggests new approach to fabrication of optielectronic and photonic components. It employs a new method of controllable laser-assisted deposition of the target material from a liquid being in direct contact with the surface of solid-state substrate. “Clean room” in that case is formed inside a gas bubble directly on the interface between the liquid and substrate, while laser beam provides a flexible means for forming required deposition pattern on the substrate surface.
The possibility of laser-assisted deposition of some oxides on sapphire under exposure of its interface with various aqueous solutions has been demonstrated recently [S. I. Dolgaev, V. V. Voronov, and G. A. Shafeev, Heteroepitaxial growth of oxides on sapphire induced by laser radiation in the solid-liquid interface, Appl. Phys., A66, 87-92 (1998)]. The deposition of Cr2O3, Fe2O3, and MnO2 has been experimentally observed using aqueous solutions of CrO3, FeCl3, and KMnO4, respectively [V. V. Voronov, S. I. Dolgaev, G. A. Shafeev, Heteroepitaxial growth of films under laser irradiation of the interface sapphire/absorbing liquid, Reports of Russian Academy of Sciences, 358(4), 465 (1998); S. I. Dolgaev, N. A. Kirichenko, and G. A. Shafeev, Deposition of nanostructured Cr2O3 on amorphous substrates under laser irradiation of the solid-liquid interface, Appl. Surf. Sci., 138-139, 449-454 (1999)]. In this instance the deposited oxide film grows epitaxially on the sapphire. On the contrary, in the case of an amorphous transparent solid, e.g., glass, the deposit is amorphous and is made of nanoclusters of the corresponding oxide. Similar results have been reported later on deposition of an amorphous TiO2 on a glass substrate under laser irradiation of an aqueous solution of TiCl3 [G. A. Shafeev. Dynamics of TiO2 deposition from TiCl3 aqueous solution induced by a cw laser radiation, Physics of Vibrations, 7, 197 (1999)].
Based on these recent findings, the present invention proposes general method of laser-assisted fabrication of different micro-optical optoelectronic and photonic components using deposition of target inorganic or organic materials from a liquid onto various solid-state substrates. In one preferred embodiment, the material deposition process is used to form a micro-lens directly on optical fiber end face or on its side surface. Such a micro-lens can dramatically improve efficiency of coupling of various lasers, including laser diodes, into the optical fiber. The micro-lens can also be fabricated directly on light emitting devices, such as laser diodes or laser diode arrays, performing beam-collimating functions as required for fabrication of different fiber-optic components. In another preferred embodiment the material deposition process is used for fabrication of various integrated optical components on different substrates, including waveguides, gratings and micro-optical elements. The process provides a possibility of simple fabrication of many different active and passive micro-optical elements employing the simple procedure of direct laser beam writing of the required structure.
The proposed general method can be applied to fabrication of many different inorganic or organic micro-optical components and devices onto various amorphous and crystalline solid-state substrates.